The present invention relates to filters for industrial baghouses and more particularly to a fastener for securing the end of an outer strap placed around a baghouse cartridge filter.
Baghouses utilizing cartridge filters are commonly used to remove particulates in industrial situations. The baghouses include two large chambers, or plenums, that are divided by a tube sheet preferably formed from sheet metal. The tube sheet comprises a plurality of openings for receipt of air filter cartridges, preferably containing fabric filtration elements. Fabric filter media having longitudinal pleatings are particularly effective for removing particulates. One such air filter cartridge is disclosed in U.S. Pat. No. 5,632,791 to Reinout G. Oussoren and Jack T. Clements, herein incorporated by reference in its entirety.
Air containing unwanted particulates is forced into the first plenum by a forced air means such as a fan. The air passes from the first plenum to the second plenum via the air filter cartridges held by the tube sheet. The particulates are retained on the outer surface of the fabric filter element of the cartridge filter, and the cleaned air is directed into the second plenum and exits the baghouse through an exhaust passageway.
Oftentimes, the baghouses are operated continuously for relatively long periods of time. As with most physical filtration media, the effectiveness of the fabric filters diminishes as particulates collect on the outer surfaces of the filter elements and minimize the airflow through the filters. To remove undesirable accumulations of particulates on the baghouse filters, air may be pulsed through the baghouse cartridge filters from the second plenum to the first plenum. The pulses dislodge the particulates lodged on the exterior of the filter, and the loose particulates are removed from the first plenum. Accordingly, the effectiveness of the baghouse is greatly increased without having to repeatedly remove and replace the cartridges. One such apparatus for cleaning baghouse filters is disclosed in U.S. Pat. No. 5,837,017 to March Santschi and Gregg Zolttek, herein incorporated by reference in its entirety.
However, the cleaning process is not without drawbacks. For instance, the structural integrity of the cartridge filters begins to deteriorate due to the relatively strong forces applied to the cartridge walls. Specifically, the cartridge walls tend to deflect outwardly when the pulses of air are forced from the interior to the exterior of the cartridge walls during the cleaning process. Thus, belt-like straps tightly secured about the circumference of the cartridges have been used to minimize the bending and bowing of the pleated filters. Typically, the ends of the straps are fastened by opposing snap means on either end of the straps. However, the snap means do not provide the desired strength needed in baghouse applications. Moreover, the snap heads tend to have relatively high profiles extending beyond the curved face of the strap. The snaps often sheer when the cartridges are slid into the openings in the baghouse tube sheets. Further, attempts to spot weld the opposing ends of the straps to one another do not provide the desired strength. Also, attempts to place a rivet through corresponding holes on either end of the strap have failed due to the difficulty associated with placing a washer behind the strap while applying the rivet.
Accordingly, the need exists for a method and apparatus to secure the ends of a strap positioned about a baghouse cartridge filter that does not sheer when the cartridges are placed in the tube sheet while providing enough strength to prevent failure due to the high forces during the cleaning process.
It is an object of the present invention to overcome the problems associated with the prior art.